Method to determine the roll angle of a motorcycle

ABSTRACT

A method to determine a roll angle (λE) of a vehicle, wherein the roll angle (λE) is calculated as a combination of at least a first roll angle variable (λ1) and a second roll angle variable (λ2), wherein the first roll angle variable (λ1) is determined from an acquired rolling rate ({dot over (λ)}m) of the vehicle using a first method, wherein the second roll angle variable (λ2) is determined from one or more further vehicle movement dynamics characteristic variables using a second method.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase Application of PCTInternational Application No. PCT/EP2017/055104, filed Mar. 3, 2017,which claims priority to European Patent Application No. 16465506, filedMar. 4, 2016, the contents of such applications being incorporated byreference herein.

FIELD OF THE INVENTION

The invention is directed to a method and a device for determining theroll angle of a motorcycle and/or a vehicle.

BACKGROUND OF THE INVENTION

Modern motorcycle antilock brake systems (ABS) and integral brakesystems are very highly developed and therefore relatively reliable forbraking operations during straight-ahead travel and braking operationsin moderately sloping positions. In relatively severely slopingpositions, the parameters of the brake system (for example thedistribution of the braking force, the gradient of the braking pressureand the control strategy) have to be adapted to cornering in order alsoto ensure safe braking when cornering occurs. Knowledge of the slopingposition angle (roll angle) is essential for this. However, turninglight systems, chassis systems and future vehicle movement dynamicscontrol systems also require the roll angle as an input variable. Knownsystems for measuring the roll angle during driving are either tooinaccurate or too expensive for series applications. The underlyingmeasurement principles for determining the roll angle are eithersuitable only for steady-state situations or only for non-steady-statetravel situations.

Document DE 100 39 978 C2, incorporated by reference herein, discloses adevice for measuring the angle of inclination with respect to thedirection of gravity or the direction of the resulting contact forcewhich comprises a sensor arrangement and an evaluation unit which isconnected in an electrically conductive fashion, in which case thesensor arrangement has two acceleration sensors, and the evaluation unitcalculates the angle of inclination on the basis of the measuredacceleration values.

Document DE 42 44 112 C2, incorporated by reference herein, discloses anantilock brake system for motorcycles which comprises, inter alia, anauxiliary circuit which calculates the angle of the sloping position ofthe vehicle by means of two acceleration sensors.

A method for determining the roll angle and the pitch angle of atwo-wheeled vehicle using an adaptive filter is described in WO02/01151, incorporated by reference herein.

Document EP 1 989 086 81, incorporated by reference herein, discloses aMethod to determine the roll angle of a motorcycle.

SUMMARY OF THE INVENTION

An aspect of the invention is a method and a device for determining theroll angle of a motorcycle and/or a vehicle, which permits more reliabledetermination of the roll angle compared to existing realizations,particularly in several and/or most and/or all driving conditions,and/or a higher level of accuracy compared to existing realizations,particularly in several and/or most and/or all driving conditions.Particularly in this context, the cost of implementing the method and ofmanufacturing the device are to be low.

Alternatively preferred, an aspect of the invention is based on theobject of making available a method and a device for determining theroll angle of a motorcycle and/or of a vehicle which permits reliabledetermination of the roll angle with a high level of accuracy at thesame time. In this context, the cost of implementing the method and ofmanufacturing the device are to be low.

Preferably the method according to an aspect of the invention is basedon the idea of combining the results or information from two or moredifferent methods for determining a roll angle with one another in orderthus to obtain a sufficiently accurate roll angle using cost-effectivesensors in all travel situations (steady-state or non-steady-state). Forthis purpose, a first roll angle variable is determined from an acquiredrolling rate of the vehicle using a first method. At least a second rollangle variable is determined from one or more further vehicle movementdynamics characteristic variables. The roll angle is then calculatedfrom the at least two roll angle variables which are determined.

Preferably the method according to an aspect of the invention is basedon the idea to determine a roll angle of a vehicle, wherein the rollangle is calculated as a combination of at least a first roll anglevariable and a second roll angle variable, wherein the first roll anglevariable is determined from an acquired rolling rate of the vehicleusing a first method, wherein the second roll angle variable isdetermined from one or more further vehicle movement dynamicscharacteristic variables using a second method.

It is preferred that the combination assures eliminating an offsetand/or noise of the first roll angle variable and/or of the second rollangle variable.

It is preferred that the combination comprises multiple levels, whereineach level comprises at least one filtering step and at least onecombination step.

It is particularly preferred that the combination comprises two levels,wherein the first level comprises four filtering steps, particularly twolow pass filter and two high pass filter, and two combination steps,wherein the second level comprises two filtering steps, particularly onelow pass filter and one high pass filter, and one combination step.

It is preferred that the first roll angle variable is fed to at leasttwo filtering steps, particularly to at least two high pass filterand/or to two high pass filter.

It is preferred that the second roll angle variable is fed to at leasttwo filtering steps, particularly to at least two low pass filter and/orto two low pass filter.

It is preferred that the number of levels is x, wherein the y-st levelcomprises 2̂(x−y+1) filtering steps and 2̂(x−y) combination steps, whereinthe output of level y is the input of level y+1, wherein in particularin the y-st level 2̂(x−y) cutoff frequencies are applied.

It is particularly preferred that y is the respective level of the totalnumber of levels x.

It is preferred that the first roll angle variable has differentcharacteristics than the second roll angle variable.

It is preferred that at least the first method provides roll anglevalues with particularly high accuracy for rapidly changing roll anglevalues.

It is preferred that at least the second method provides roll anglevalues with particularly high accuracy for steady roll angle values.

It is preferred that the second roll angle variable is determined from ayaw rate of the vehicle and a vehicle velocity.

It is preferred that the second roll angle variable is determined from alateral acceleration and a vertical acceleration of the vehicle.

It is preferred that the vehicle is a motorcycle. Particularlycompensation methods are applied fitted to motorcycle dynamics.

It is preferred that the vehicle is no airplane.

It is preferred that cross effects between angular rates due to theinclinations of the measurement system are eliminated based on theinertial measurement.

Particularly preferred the cross effect elimination is based on a pitchangle, wherein the pitch angle is estimated based on accelerationmeasurements.

Particularly preferred the pitch angle is estimated based onlongitudinal acceleration which is fixed to the motorcycle and/or basedon vertical acceleration which is fixed to the motorcycle and/or basedon the overall acceleration of the motorcycle and/or based on thegravity.

Particularly preferred the cross effect elimination increases theaccuracy of the roll rate and/or the accuracy of the yaw rate.

Particularly preferred the cross effect, elimination increases theprecision of the first method determining the first roll angle variableand/or the precision of the second method determining the second rollangle variable.

It is preferred that one of the roll angle variable determinationmethods applies a resettable integrator in combination with a resettablehigh-pass filter to eliminate roll rate offset effects.

It is preferred that the first method applies an integrator fordetermining the first roll angle variable, wherein the integrator andsubsequent filters, particularly direct subsequent high-pass filters,are resetted essentially simultaneous as soon as the output of theintegrator reaches a predefined threshold.

It is preferred that one of the roll angle variable determinationmethods is using a compensation method to increase the precision of thecalculation based on the vertical centrifugal acceleration. Particularlythe compensation method is based on an estimated centrifugal force,wherein the estimation of the centrifugal force is based on the rollrate and/or on a radius, wherein the radius is essentially the distancebetween the tire contact point on the ground and a center of gravity ofthe motorcycle.

Particularly preferred the compensation method increases the accuracy oflateral acceleration based on a comparison of vertical acceleration andestimated centrifugal force.

Particularly preferred the compensation method increases the precisionof the second method determining the second roll angle variable.

It is preferred that one of the roll angle variable determinationmethods is using a compensation method to increase the precision of thecalculation based on the common effect of the lateral acceleration andthe roll rate. Particularly the compensation method is based on anestimated rapid leaning force, wherein the estimation of the rapidleaning force is based on the derivative of the roll rate and/or adistance between the tire contact point on the ground and the mountinglocation of the lateral acceleration sensor.

Particularly preferred the compensation method increases the accuracy oflateral acceleration based on a comparison of lateral acceleration andestimated rapid leaning force.

Particularly preferred the compensation method increases the precisionof the second method determining the second roll angle variable.

It is preferred that one of the roll angle variable determinationmethods is using a compensation method to increase the precision of thecalculation by compensating the difference and/or discrepancy betweenthe total roll angle and the physically active roll angle. Particularlythe compensation method is based on a comparison between the verticalacceleration to the gravity and on the yaw rate.

Particularly preferred the compensation method increases the accuracy oflateral acceleration.

Particularly preferred the compensation method increases the precisionof the second method determining the second roll angle variable.

It is preferred that the combination takes place in a frequency domain.

It is preferred that an amplitude of high frequencies of the first rollangle variable of the first method is weighted higher than an amplitudeof high frequencies of the second roll angle variable of the secondmethod

It is preferred that an amplitude of low frequencies of the second rollangle variable of the second method is weighted higher than an amplitudeof low frequencies of the first roll angle variable of the first method

It is preferred that an amplitude of mid frequencies are weightedsimilarly.

It is preferred that a first combination combines the first roll anglevariable high-passed filtered with a first cutoff frequency and thesecond roll angle variable low-passed filtered essentially with thefirst cutoff frequency.

It is preferred that a second combination combines the first roll anglevariable high-passed filtered with a second cutoff frequency and thesecond roll angle variable low-passed filtered essentially with thesecond cutoff frequency.

It is preferred that a third combination combines a first combined rollangle variable, which is the result of the first combination, low-passedfiltered with a third cutoff frequency and the second combined rollangle variable, which is the result of the second combination,high-passed filtered essentially with the third cutoff frequency.

It is preferred that the first, the second and the thirdcutoff-frequencies are different.

It is preferred that the first cut-off-frequency is in the range fromapproximately 0.01 Hz to approximately 0.50 Hz. Particularly preferredthe first cut-off-frequency is essentially 0.1 Hz.

It is preferred that the second cut-off-frequency is in the range fromapproximately 0.1 Hz to approximately 10 Hz. Particularly preferred thesecond cut-off-frequency is essentially 2 Hz.

It is preferred that the third cut-off-frequency is in the range fromapproximately 0.05 Hz to approximately 2 Hz. Particularly preferred thethird cut-off-frequency is essentially 0.2 Hz.

It is preferred that the third cutoff frequency lies between the firstcutoff frequency and the second cutoff frequency.

According to one preferred embodiment of the method according to anaspect of the invention the combination is calculated by multiple levelsof filtering and summing in order to improve noise cancellation and toreduce offset effects.

According to one preferred embodiment of the method according to anaspect of the invention the roll angle is calculated as a combination ofroll angles calculated by methods providing roll angle variables withdifferent properties.

According to one preferred embodiment of the method according to anaspect of the invention during the combination at least six filteroperations (low-, high-, bandpass) are applied and at least threedifferent cutoff frequencies are used.

According to one preferred embodiment of the method according to anaspect of the invention, the roll angle is calculated from the rollangle variables by addition.

Furthermore, it is preferred that the roll angle variables are filteredbefore the roll angle is calculated from them.

It is advantageous to filter the rolling rate with a high pass filterbefore it is used to calculate the first roll angle variable. Thisincreases the fault tolerance of the method according to an aspect ofthe invention. It has proven particularly advantageous to use a highpass filter with a cut-off frequency of approximately 0.01 Hz for thefiltering.

The rolling rate is preferably acquired by means of a rotational speedsensor which is mounted on the vehicle. The position of the rotationalspeed sensor on the motorcycle is not relevant since the rotationalspeeds on the entire vehicle are the same.

A first roll angle variable is preferably calculated from the rollingrate by integration over time. For small pitch angles, a rolling ratewhich is fixed to the motorcycle and a rolling rate which is fixed tothe roadway closely resemble each other, and integration of the rollingrate which is fixed to the motorcycle results briefly in a roll anglevariable which represents the roll angle.

According to one preferred embodiment of the method according to anaspect of the invention, the first roll angle variable is filtered witha high pass filter before it is used to calculate a roll angle. Thisreduces falsifications of the roll angle due to measurement errors ofthe rotational speed sensor. A high pass filter with a cut-off frequencyof approximately 0.05 Hz is particularly preferably used.

Furthermore it is advantageous to filter the second roll angle variablewith a low pass filter before it is used to calculate the roll anglesince the relationships between the vehicle movement dynamicscharacteristic variables which form the basis of the determination ofthe second roll angle variable apply only in the case of steady-statecornering. A high pass filter with a cut-off frequency of approximately0.05 Hz is particularly preferred.

The cut-off frequency of the low pass filter which is used to filter thesecond roll angle variable preferably has the same value, orapproximately the same value, as the cut-off frequency of the high passfilter which is used to filter the first roll angle variable. Thisensures uninterrupted determination of the roll angle over the entirefrequency range. The cut-off frequency particularly preferably is in therange from approximately 0.01 Hz to approximately 0.10 Hz. The cut-offfrequency which is used for the high pass filter and the low pass filteris quite particularly preferably 0.05 Hz. The lowest possible cut-offfrequency is advantageously selected.

It is preferred that when more than two roll angle variables are added,the cut-off frequencies of the high pass filter, bandpass and filter lowpass filter which are used are selected in such a way that the rollangle is determined over the entire frequency range.

According to one preferred embodiment of the method according to anaspect of the invention, the second roll angle variable is acquiredeither from the product of a yaw rate and a vehicle velocity, or from ayaw rate, a vehicle velocity and a vertical acceleration of the vehicle,or from a vertical acceleration of the vehicle, or from a verticalacceleration and a lateral acceleration of the vehicle. The yaw rate isparticularly preferably determined by means of a rotational speedsensor. The vehicle velocity is particularly preferably determined fromthe measurement variables of at least one rotational speed sensor.

The roll angle variable or variables is/are preferably determined fromthe respective vehicle movement dynamics characteristic variable orvariables on the basis of one or more characteristic curves which arestored in a control unit or at least one characteristic diagram which isstored in a control unit. When the second roll angle variable isacquired from the yaw rate and vehicle velocity, the determination isparticularly preferably carried out by means of a characteristic diagramor a characteristic curve.

Alternatively, the second roll angle variable or variables is/arepreferably calculated from the respective vehicle movement dynamicscharacteristic variable or variables on the basis of a calculationalgorithm.

According to one preferred development of the method according to anaspect of the invention, two or more second roll angle variables aredetermined in different ways from the vehicle movement dynamicscharacteristic variables. These second roll angle variables which aredetermined in different ways are then used for plausibility checking ofthe roll angle. For the purpose of plausibility checking, the secondroll angle variables which are determined in different ways and/or fromdifferent vehicle movement dynamics characteristic variables areparticularly preferably compared with one another. Alternatively, a rollangle is respectively calculated from the first roll angle variable andone of the second roll angle variables, and these roll angles arecompared with one another. Quite particularly preferably, at least oneof the second roll angle variables is determined from at least oneacceleration of the vehicle.

A malfunction of a sensor which is being used is preferably detected onthe basis of the comparison of the second roll angle variables or rollangles which are determined in different ways. If the second roll anglevariable which is calculated from the values of a sensor differs fromthe other roll angle variables, a malfunction of the sensor is possiblyoccurring. Rapid and simple detection of a faulty sensor is thereforepossible. In this way, a fault in an acceleration sensor is particularlypreferably detected.

It is likewise preferred to use the acquired acceleration values todetermine an offset of the rotational speed sensor in order to determinethe rolling rate.

A linearity fault of the rolling rate is advantageously determined usingthe offset which is determined in this way. Said linearity fault canthen be used to correct the rolling rate and the accuracy of the methodaccording to an aspect of the invention is therefore improved further.

The acceleration sensors are preferably also used to calculate the rollangle when the vehicle is stationary.

According to a further preferred embodiment of the method according toan aspect of the invention, the roll angle is calculated by weightedsumming from the at least two roll angle variables which are determined,with the corresponding weighting parameters being adapted as a functionof the current travel situation. The travel situation is detected hereon the basis of at least one of the following variables: engine speed,engine torque, steering angle, vehicle velocity, vehicle acceleration,wheel speeds, state of the roadway, rolling rate, yaw rate, roll angleacceleration, yaw angle acceleration, roll angle, wheel slip, vehicleload, inclination of the roadway. The calculated roll angle isparticularly preferably used, during the optimization of the weightingparameters, as an input variable for assessing the travel situation(iterative calculation of the roll angle).

In addition to the first roll angle variable which is determined fromthe rolling rate, a second roll angle variable is preferably determinedfrom a vertical acceleration and a lateral acceleration of the vehicle,and a further second roll angle variable is determined from the productof a yaw rate and a vehicle velocity, and the roll angle is calculatedfrom the three roll angle variables, in particular filtered with a highpass filter or low pass filter, by weighted summing with weightingparameters, the weighting parameters being adapted as a function of thecurrent travel situation, which is detected on the basis of at least oneof the following variables: engine speed, engine torque, steering angle,vehicle velocity, vehicle acceleration, wheel speeds, state of theroadway, rolling rate, yaw rate, roll angle acceleration, yaw angleacceleration, roll angle, wheel slip, vehicle load and inclination ofthe roadway.

It is likewise preferred for the properties of the filters which areused to filter the roll angle variables to be selected as a function ofthe current travel situation. The cut-off frequencies of the filters areparticularly preferably selected as a function of the current travelsituation.

The device according to an aspect of the invention is preferably basedon the idea that an adding circuit is used to add at least two rollangle variables to form a roll angle, in which case a first roll anglevariable is determined from a rolling rate of the vehicle, and a secondroll angle variable is determined using at least one vehicle movementdynamics characteristic variable.

According to one development of the device according to an aspect of theinvention, said device has at least one evaluation unit which containsan integrating circuit with which the first roll angle variable isdetermined from the rolling rate by integration.

The device according to an aspect of the invention advantageouslycomprises at least one evaluation unit with a high pass filter withwhich the first roll angle variable is filtered before it is used tocalculate the roll angle.

Particularly preferred is the integrating circuit, with which the firstroll angle variable is determined, designed as a resettable integrationcircuit.

Particularly preferred is at least one high pass filter, with which thefirst roll angle variable is filtered, designed as a resettable highpass filter.

More particularly preferred is the at least one high pass filter linkedby a reset signal to the resettable integration circuit.

More particularly preferred the device comprises three evaluation unitseach with a high pass filter, wherein with the first high pass filterand with the second high pass filter the first roll angle variable isfiltered, wherein with the third high pass filter a combination of thefirst roll angle variable and the second roll angle variable isfiltered.

Furthermore, the device preferably comprises, in at least one evaluationunit, a low pass filter with which the second roll angle variable isalso filtered before it is used to calculate the roll angle.

More particularly preferred the device comprises three evaluation unitseach with a low pass filter, wherein with the first low pass filter andwith the second low pass filter the second roll angle variable isfiltered, wherein with the third low pass filter a combination of thefirst roll angle variable and the second roll angle variable isfiltered.

The low pass filter for filtering the second roll angle variablepreferably has the same or approximately the same cut-off frequency asthe high pass filter for filtering the first roll angle variable. As aresult, uninterrupted determination of the roll angle is ensured overthe entire frequency range during the subsequent addition of the rollangle variables.

According to one preferred embodiment of the device according to anaspect of the invention, at least one, particularly three, evaluationunit comprises a combination unit, wherein each combination unitcombines two roll angle variables.

Particularly preferred the device comprises one evaluation unit e.g. amicroprocessor and/or a microcontroller, wherein the evaluation unit isdesigned in such a way that it performs the required filtering and/orcombinations and/or eliminations and/or compensations.

It is preferred that the device to determine the roll angle is designedas a sensor cluster or sensor system.

According to one preferred embodiment of the device according to anaspect of the invention, at least one evaluation unit comprises acircuit with which the second roll angle variable is determined from ayaw rate and a vehicle velocity, or from a yaw rate, a vehicle velocityand a vertical acceleration of the vehicle, or from a verticalacceleration of the vehicle, or from a vertical acceleration and alateral acceleration of the vehicle.

According to one preferred embodiment of the device according to anaspect of the invention, at least one evaluation unit comprises acircuit with which cross effects between angular rates, e.g. due to theinclinations of the measurement system, are eliminated, particularlybased on the inertial measurement.

According to one preferred embodiment of the device according to anaspect of the invention, at least one evaluation unit comprises acircuit with which a compensation method to increase the precision ofthe calculation based on the vertical centrifugal acceleration isperformed.

According to one preferred embodiment of the device according to anaspect of the invention, at least one evaluation unit comprises acircuit with which a compensation method to increase the precision ofthe calculation based on the common effect of the lateral accelerationand the roll rate is performed.

According to one preferred embodiment of the device according to anaspect of the invention, at least one evaluation unit comprises acircuit with which a compensation method to increase the precision ofthe calculation by compensating the difference and/or discrepancybetween the total roll angle and the physically active roll angle isperformed. Particularly the compensation method is based on a comparisonbetween the vertical acceleration to the gravity and on the yaw rate.

According to one preferred embodiment of the device according to anaspect of the invention, a y-st level comprises 2^(x−y+1) filters and2^(x−y) combination units. Particularly the number of levels is at least2 and/or is 2. Particularly preferred each levels comprises the samenumber of low pass filters as high pass filters.

The means for acquiring the rolling rate and/or the means for acquiringthe yaw rate of the vehicle are/is preferably one or more rotationalspeed sensors. A rotational speed sensor or sensors which is/are alreadyknown within the scope of vehicle movement dynamics control systems inmotor vehicles is/are particularly preferably used.

The means for acquiring the velocity of the vehicle is preferably atleast one wheel speed sensor. Such a wheel speed sensor is usuallyalready provided in the vehicle within the scope of an antilock brakesystem.

According to one preferred embodiment of the device according to anaspect of the invention, the means for acquiring at least oneacceleration value is an acceleration sensor or a group of accelerationsensors. The sensor is particularly preferably a sensor of a vehiclemovement dynamics control system, quite particularly preferably a sensorof an electronic stability program (ESP). Such sensors are technicallymature and therefore can be used without additional development costs.

One advantage of an aspect of the invention is, that by using sensorswhich are already known in the prior art, cost-effective and at the sametime accurate determination of the roll angle of the vehicle ispossible.

An aspect of the invention also comprises the use of a method accordingto an aspect of the invention in at least one of the following systems:electronically controlled brake system, turning light system, chassissystem, electrical steering system and vehicle movement dynamics controlsystem.

BRIEF DESCRIPTION OF THE DRAWINGS

Further preferred exemplary embodiments of aspects of the inventionemerge from the subclaims and from the subsequent description on thebasis of figures, of which

FIG. 1 is a schematic illustration of a motorcycle in a slopingposition,

FIG. 2 is a schematic illustration of a first exemplary embodiment of amethod according to an aspect of the invention,

FIG. 3 is a schematic illustration of a second exemplary embodiment of amethod according to an aspect of the invention,

FIG. 4 is a schematic illustration of a third exemplary embodiment of amethod according to an aspect of the invention,

FIG. 5 is a schematic illustration of an exemplary method fordetermining a roll angle,

FIG. 6 is a schematic illustration of a fourth exemplary embodiment of amethod according to an aspect of the invention,

FIG. 7 is a schematic illustration of an exemplary method for adaptivecalculation of a roll angle for use in the fourth exemplary embodimentillustrated in FIG. 7,

FIG. 8 is a schematic illustration of an exemplary method for adaptivecalculation of a roll angle,

FIG. 9 is a schematic illustration of measured acceleration,particularly for a nonzero pitch angle, and

FIG. 10 is a schematic illustration of an exemplary method of acombination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The core of the device or of the method for determining the roll angle(angle of inclination) of a vehicle, in particular a motorcycle, duringdriving is the combination of at least two individual calculationresults (for steady-state travel and non-steady-state travel), inparticular by means of a specific filter.

FIG. 1 is a schematic illustration of a number of variables which arerelevant to the method according to an aspect of the invention. Amotorcycle 2 travels in a sloping position on roadway 1. A tire 3 of themotorcycle 2 is illustrated in sectional form. Line 4 represents thedirection of the perpendicular to the roadway, and line 5 represents theaxis of symmetry of the motorcycle 5. At the center of gravity SP of themotorcycle 2, the coordinate system which is fixed to the motorcycle isindicated by the vertical axis z^(M), which is fixed to the motorcycleand which runs parallel to the axis of symmetry of the motorcycle 5, andthe transverse axis y^(M), which is perpendicular thereto and is fixedto the motorcycle. Line 6 represents the connecting line, projected intothe y/z plane, between the center of gravity SP of the motorcycle 2 andthe wheel contact point or wheel contact line RAP. The total roll angleλ_(ges) corresponds to the angle between the perpendicular 4 to theroadway and the plane 5 of symmetry of the vehicle, and the physicallyactive roll angle λ_(th) corresponds to the angle between theperpendicular 4 to the roadway and the line 6. By way of example, one ormore sensors 7, for example a rolling rate sensor for determining therolling rate {dot over (λ)}^(M) which is fixed to the motorcycle and/ora yaw rate sensor for determining the yaw rate {dot over (ψ)}^(M) whichis fixed to the motorcycle, is/are arranged laterally on the motorcycle2. Alternatively or additionally, one or more sensors or a sensorcluster 8 can be arranged on the motorcycle 2, in particular in theregion of the center of gravity SP, these being, for example, a yaw ratesensor for determining the yaw rate {dot over (ψ)}^(M) which is fixed tothe motorcycle and/or acceleration sensor or sensors for determining thevertical acceleration {umlaut over (z)}^(M) which is fixed to themotorcycle and/or the lateral acceleration ÿ^(M) which is fixed to themotorcycle. The position of the rolling rate sensor and the position ofthe yaw rate sensor on the motorcycle 2 are advantageously not relevant.

In customary tires, the total roll angle λ_(ges) is approximately 10% to20% above the physically active roll angle λ_(th). The differencebetween the total roll angle λ_(ges) and the physically active rollangle λ_(th) is also referred to as the additional roll angle λ_(ZS).The following therefore applies:

λ_(ges)=λ_(ZS)+λ_(th)  (1)

In customary tires, the additional roll angle λ_(ZS) which isconditioned by the width of the tire is, as has already been mentionedabove, of the order of magnitude of approximately 10% to 20% of thephysically active roll angle λ_(th). Since λ_(ZS) is small compared toλ_(th), the total roll angle λ_(ges) is often approximated by thephysically active roll angle λ_(th):

λ_(ges)≈λ_(th)

For small pitch angles, the rolling rate {dot over (λ)}^(M) which isfixed to the motorcycle and the rolling rate {dot over (λ)}^(roadway)which is fixed to the roadway are similar to one another. Integration ofthe rolling rate {dot over (λ)}^(M) gives rise to the (total) roll angleλ_(ges) (this corresponds to the first roll angle variable λ₁ in theexemplary embodiments in FIGS. 2, 3 and 4).

A first exemplary embodiment of a method according to an aspect of theinvention is illustrated schematically in FIG. 2. The integration 10over time of the rolling rate {dot over (λ)}^(M) which is fixed to themotorcycle is here a first calculation result (first roll angle variableλ₁). For example, the calculation result λ₁ is filtered with the highpass filter 11, which has, for example, a cut-off frequency f_(Trenn) of0.05 Hz. In the illustrated first exemplary embodiment, the secondcalculation result (second roll angle variable λ₂) is obtained as afunction 13 of the product 12 of the yaw rate {dot over (ψ)}^(M) whichis fixed to the motorcycle and the velocity v of the motorcycle. Forexample, the calculation result λ₂ is filtered with the low pass filter14, which has, for example, the same cut-off frequency f_(Trenn) as thehigh pass filter 11, for example 0.05 Hz. In order to determine the rollangle λ_(E) of the motorcycle, the calculation result λ₁ of theintegration 10 over time of the rolling rate λ^(M) which is fixed to themotorcycle and the calculation result λ₂ is added to a function 13 ofthe product 12 of the yaw rate {dot over (ψ)}^(M) which is fixed to themotorcycle and the velocity v (block 15).

The calculation of the first roll angle variable λ₁ by integration 10 ofthe rolling rate {dot over (λ)}^(M) which is fixed to the motorcycleapplies both to steady-state and to non-steady-state travel. However,the calculation by integration 10 of the measurement error of therolling rate λ^(M) is not long-term stable, i.e. the result is validonly for a brief time. Depending on the design and accuracy of therolling rate sensor used, the increase in the measurement error(referred to as drift) is between 1 degree/minute and 1 degree/second.

In order to avoid overflow errors during the integration 10, it ispossible, according to an exemplary embodiment which is not illustrated,to transfer the functions of integration 10 and high pass filter 11 intoan equivalent low pass filter with additional gain.

The calculation of the second roll angle variable λ₂ from the yaw rate{dot over (ψ)}^(M) which is fixed to the motorcycle and the vehiclevelocity v applies only to steady-state cornering. Function 13 isdependent on the tire geometry and the dynamic tire behavior of themotorcycle.

The filters 11, 14 used are usually first-order PT₁ elements. Thecut-off frequency f_(Trenn) is, for example, in the range fromapproximately 0.01 Hz to approximately 0.10 Hz.

The following explanation serves to substantiate the relationshipbetween the yaw rate {dot over (ψ)}^(M), vehicle velocity v and rollangle λ:

For steady-state cornering the following applies: the yaw rate {dot over(ψ)}^(M) which is fixed to the motorcycle is provided by the yaw rate{dot over (ψ)}^(roadway) which is fixed to the roadway and multiplied bythe cosine of the total roll angle λ_(ges), and by the pitch anglevelocity {dot over (ν)}_(roadway), wherein, however, the pitch anglevelocity {dot over (ν)}_(roadway) is zero for steady-state travel ({dotover (ν)}_(roadway)=0), with the result that the second term sinλ_(g)·{dot over (ν)}_(roadway) in equation (2) is eliminated:

{dot over (ψ)}^(M)=cos λ_(ges)·{dot over (ψ)}^(roadway)−sin λ_(ges)·{dotover (ν)}_(roadway)=cos λ_(ges)·{dot over (ψ)}^(roadway)  (2)

For steady-state cornering, the following relationships also applybetween the lateral acceleration {dot over (y)}^(h) in thehorizontalized coordinate system (coordinate system which is rotatedabout the x axis with respect to the coordinate system which is fixed tothe motorcycle, with the result that the horizontalized lateralacceleration {dot over (y)}^(h) extends parallel to the roadway), thevehicle velocity v, the yaw rate {dot over (ψ)}_(roadway) which is fixedto the roadway, the tangent of the effective roll angle λ_(th) and thegravitational acceleration g:

$\begin{matrix}{{\overset{¨}{y}}^{h} = {v \cdot \psi^{roadway}}} & (3) \\{{\tan \; \lambda_{th}} = \frac{v \cdot {\overset{.}{\psi}}^{roadway}}{g}} & (4)\end{matrix}$

Insertion of (2) into (4) provides:

$\begin{matrix}{{\tan \; \lambda_{th}} = {\frac{v \cdot {\overset{.}{\psi}}^{roadway}}{g} = \frac{v \cdot {\overset{.}{\psi}}^{M}}{\cos \; {\lambda_{ges} \cdot g}}}} & (5) \\{{\sin \; {\lambda_{th} \cdot \frac{\cos \; \lambda_{ges}}{\cos \; \lambda_{th}}}} = \frac{v \cdot \psi^{M}}{g}} & \left( {6a} \right)\end{matrix}$

Assuming that λ_(ges)=λ_(th), this can also be simplified to yield:

$\begin{matrix}{{\sin \; \lambda_{th}} \approx \frac{v \cdot {\overset{.}{\psi}}^{M}}{g}} & \left( {6b} \right)\end{matrix}$

Therefore, the roll angle λ_(th) is a function f of the product {dotover (ψ)}_(M)·v of the yaw rate {dot over (ψ)}^(M) which is fixed to themotorcycle and the velocity v of the motorcycle:

$\begin{matrix}{{f\left( \lambda_{th} \right)} = \frac{{\overset{.}{\psi}}^{M} \cdot v}{g}} & (7)\end{matrix}$

The functional relationship f(λ_(th)) or the above equation (7) cannotbe solved in a closed fashion. For this reason, a numerically acquiredcharacteristic curve is used (block 13) in order to determine the rollangle λ_(th) (according to the exemplary embodiment illustrated in FIG.2 the roll angle variable λ₂) from the product (block 12) of the yawrate {dot over (ψ)}_(M) which is fixed to the motorcycle and thevelocity v.

FIG. 3 is a schematic illustration of a second exemplary embodiment of amethod according to an aspect of the invention. In this exemplaryembodiment also, the integration 10 over time of the rolling rate {dotover (λ)}^(M) which is fixed to the motorcycle is the first calculationresult (the first roll angle variable λ₁), and here too the first rollangle variable λ₁ is filtered, for example, with a high pass filter 11,with, for example, a cut-off frequency f_(Trenn) of 0.05 Hz. Theexplanation and alternative ways of calculating the first roll anglevariable λ₁ which are given further above within the scope of the firstexemplary embodiment apply here correspondingly. In contrast to thefirst exemplary embodiment, in the second exemplary embodiment thesecond calculation result (the second roll angle variable λ₂′) isdetermined essentially from the acceleration, fixed to the motorcycle,in the z direction {umlaut over (z)}^(M) (block 16). In order to takeinto account the width of the tire, the second roll angle variable λ₂′in block 17 can be multiplied by an empirical factor c. In the secondexemplary embodiment of the method according to an aspect of theinvention, the second calculation result λ₂′ is also filtered with a lowpass filter 14′ with, for example, the same cut-off frequency f_(Trenn)as that of the high pass filter 11, this being for example 0.05 Hz. Inorder to determine the roll angle λ_(E) of the motorcycle, thecalculation result λ₁ of the integration 10 over time of the rollingrate {dot over (λ)}_(M) which is fixed to the motorcycle and thecalculation result λ₂′ are added to the determination of a roll anglevariable from an acceleration, fixed to the motorcycle, in the zdirection {umlaut over (z)}^(M) (block 15′).

The filters 11, 14′ used are customarily first-order PT₁ elements. Thecut-off frequency f_(Trenn) is, for example, in the range fromapproximately 0.01 Hz to approximately 0.10 Hz.

The calculation of the second roll angle variable λ₂′ from anacceleration which is fixed to the motorcycle in the z direction {umlautover (z)}^(M) applies only to steady-state cornering. Furthermore, ifthe factor c is not taken into account (c=1), it is based on theassumption of ideally narrow tires. Furthermore, the acceleration, fixedto the motorcycle, in the z direction {umlaut over (z)}^(M) is notsubject to a sign, with the result that a further information item, forexample the acceleration, fixed to the motorcycle, in the y directionÿ_(M), can be used to define the correct sign of the roll angle λ.

The following explanation serves to substantiate the relationshipbetween the acceleration, fixed to the motorcycle, in the z direction{umlaut over (z)}^(M) and the roll angle λ:

For steady-state cornering the physically active roll angle λ_(th) isprovided by the arc cosine of the quotient of the gravitationalacceleration g with respect to the vertical acceleration {umlaut over(z)}^(M) which is fixed to the motorcycle:

$\begin{matrix}{\lambda_{th} = {\arccos \; \frac{g}{{\overset{¨}{z}}^{M}}}} & (8)\end{matrix}$

In order to define the correct sign, the lateral acceleration ÿ^(M)which is fixed to the motorcycle can be used:

$\begin{matrix}{\lambda_{th} = {{\arccos \left( {\frac{g}{{\overset{¨}{z}}^{M}}} \right)} \cdot \left( {- 1} \right) \cdot {{sign}\left( {\overset{¨}{y}}^{M} \right)}}} & (9)\end{matrix}$

Here, sign(X) is the sign function which has the value “1” if X isgreater than zero, which is “0” if X is equal to zero, and which is “−1”if X is less than zero.

As already mentioned above, the total roll angle λ_(ges) can beapproximated by the physically active roll angle λ_(th):

λ_(ges)≈λ_(th)

For example, the second roll angle variable λ₂′ is determined accordingto the equation (9) (block 16).

A third exemplary embodiment of a method according to an aspect of theinvention is illustrated schematically in FIG. 4. In this exemplaryembodiment, the integration 10 over time of the rolling rate {dot over(λ)}^(M) which is fixed to the motorcycle is also the first calculationresult (the first roll angle variable λ₁), and for example the firstroll angle variable λ₁ is also filtered here with a high pass filter 11with, for example, a cut-off frequency f_(Trenn) of 0.05 Hz. Theexplanation and alternatives for the calculation of the first roll anglevariable λ₁ which are given above within the scope of the firstexemplary embodiment apply here correspondingly. In contrast to thefirst exemplary embodiment, in the third exemplary embodiment the secondcalculation result (the second roll angle variable λ₂″) is determinedfrom two acceleration values which are fixed to the motorcycle, inparticular an acceleration, fixed to the motorcycle, in the z direction{umlaut over (z)}^(M) and an acceleration, fixed to the motorcycle, inthe y direction ÿ^(M) (block 20). The second calculation result λ₂″ isfiltered with a low pass filter 14″ with, for example, the same cut-offfrequency f_(Trenn) as that of the high pass filter 11, this being, forexample 0.05 Hz. In order to determine the roll angle λ_(E) of themotorcycle, the calculation result λ₁ of the integration 10 over time ofthe rolling rate {dot over (λ)}_(M) which is fixed to the motorcycle andthe calculation result λ₂″ is added to the determination of a roll anglevariable from two acceleration values which are fixed to the motorcycle,for example a vertical acceleration {umlaut over (z)}^(M) which is fixedto the motorcycle and a lateral acceleration ÿ^(M) which is fixed to themotorcycle (block 15″).

The filters 11, 14″ used are customarily first-order PT₁ elements. Thecut-off frequency f_(Trenn) is, for example, in the range fromapproximately 0.01 Hz to approximately 0.10 Hz.

The calculation of the second roll angle variable λ₂″ from anacceleration, fixed to the motorcycle, in the z direction {umlaut over(z)}^(M) and an acceleration, fixed to the motorcycle, in the ydirection ÿ^(M) applies only to steady-state cornering. The calculationincludes the geometry of the tire and the dynamic tire behavior of themotorcycle.

The following explanation serves to substantiate the relationshipbetween the acceleration, fixed to the motorcycle, in the z direction{umlaut over (z)}^(M), the acceleration, fixed to the motorcycle, in they direction ÿ^(M) and the roll angle λ:

As already mentioned above, the following relationship applies:

λ_(ges)=λ_(ZS)+λ_(th)  (10)

According to equation (8), for steady-state cornering the physicallyactive roll angle λ_(th) is provided by the arc cosine of the quotientof the gravitational acceleration g with respect to the verticalacceleration {umlaut over (z)}^(M) which is fixed to the motorcycle:

$\begin{matrix}{\lambda_{th} = {\arccos \left( \frac{g}{{\overset{¨}{z}}^{M}} \right)}} & (11)\end{matrix}$

Furthermore, for steady-state cornering the additional roll angle λ_(ZS)is given by the arc tangent of the quotient of the lateral accelerationÿ^(M) which is fixed to the motorcycle with respect to the verticalacceleration {umlaut over (z)}^(M) which is fixed to the motorcycle:

$\begin{matrix}{\lambda_{ZS} = {\arctan\left( \frac{{\overset{¨}{y}}^{M}}{- {\overset{¨}{z}}^{M}} \right)}} & (12)\end{matrix}$

Insertion of equations (11) and (12) into (10) provides:

$\begin{matrix}{\lambda_{ges} = {{\arccos \left( \frac{g}{{\overset{¨}{z}}^{M}} \right)} + {\arctan\left( \frac{{\overset{¨}{y}}^{M}}{- {\overset{¨}{z}}^{M}} \right)}}} & (13)\end{matrix}$

For example, the total roll angle λ_(ges) is approximated as a multiplek of the additional roll angle λ_(ZS) which is conditioned by the widthof the tire. It is therefore calculated according to the followingrelationship (block 20):

$\begin{matrix}{\lambda_{ges} = {k \cdot {\arctan\left( \frac{{\overset{¨}{y}}^{M}}{- {\overset{¨}{z}}^{M}} \right)}}} & (14)\end{matrix}$

Here, the factor k is dependent on the geometry of the tire and thedynamic tire behavior of the motorcycle. An exemplary value is k=9.7.

An advantage of the method according to an aspect of the invention isthat the roll angle λ_(E) of the motorcycle is without time delay, apartfrom the time delays caused by the sensors. The roll angle λ_(E) can bedetermined both under steady-state and non-steady-state travelconditions. Furthermore, the accuracy of the roll angle which isdetermined by a combination of two calculation methods is higher than ispossible with an individual measuring method.

The integration of the rolling rate over time is in itself not suitableas a method for acquiring a roll angle. Owing to the measuring errorwhich increases with time, this method cannot be applied directly with astandard sensor system.

A further advantage is that the manufacturing costs of a device forimplementing the method according to an aspect of the invention aresignificantly lower than a highly accurate inertial sensor system,whilst having the same level of accuracy.

Compared to the first exemplary embodiment (FIG. 2) with a determinationof the roll angle from two rotational speed signals (rolling rate {dotover (λ)}^(M) and yaw rate {dot over (ψ)}_(M)), the manufacturing costsof the device for determining the roll angle according to the second andthird exemplary embodiments from the rolling rate {dot over (λ)}_(M),and one acceleration valve {umlaut over (z)}^(M) or two accelerationvalues {umlaut over (z)}^(M), ÿ^(M), are considerably reduced. Use of asensor cluster, which is already known, for example, from the use inelectronic stability programs (ESP) in passenger cars, is appropriate.Such a sensor cluster customarily provides a rotational speed signal andone or two acceleration signals. Such a sensor cluster can, ifappropriate, be installed rotated through 90 degrees.

If the results of the integration 10 over time of the rolling rate {dotover (λ)}_(M) which is fixed to the motorcycle and the function 13 ofthe product 12 of the yaw rate if {dot over (ψ)}_(M) which is fixed tothe motorcycle and the velocity v of the motorcycle (first exemplaryembodiment) are combined, it is advantageous that the position of thesensor system on the motorcycle is not relevant since the rotationalspeeds on the entire vehicle are the same.

An aspect of the invention also relates to a method for determining theroll angle of a motor cycle during travel from the product of the yawrate {dot over (ψ)}_(M) which is fixed to the motorcycle and thevelocity of the motorcycle. FIG. 5 is a schematic illustration of acorresponding exemplary embodiment. The product is formed from a yawrate which is fixed to the motorcycle and the velocity v of themotorcycle (block 23). A roll angle variable is determined from theproduct by means of a functional relationship, which is predefined forexample in the form of a characteristic curve (block 24). After thecalculation result has been filtered with a low pass filter 25, the rollangle λ_(E) of the motorcycle is obtained.

The filter 25 is usually a first-order PT₁ element. The cut-offfrequency is, for example, in the region of approximately 1 Hz.

According to an exemplary embodiment, not illustrated, a combination ofa plurality of filters is used in order to reduce the signal peaksduring rapid slalom travel: a low pass filter (cut-off frequency ofapproximately 0.05 Hz), a high pass filter (cut-off frequency ofapproximately 0.05 Hz, gain factor of 0.5), addition of the two signalsand possibly further filtering with a low pass filter (cut-off frequencyof approximately 1 Hz) in order to smooth the signals. According to theabove explanations (equations (2) to (7)), the roll angle λ is afunction f of the product {dot over (ψ)}_(M)·v of the yaw rate {dot over(ψ)}_(M) which is fixed to the motorcycle and the velocity v of themotorcycle (see equation (7)). A numerically acquired characteristiccurve is used (block 24) to determine the roll angle λ from the product(block 23) of the yaw rate {dot over (ψ)}_(M) which is fixed to themotor cycle and the velocity v.

The manufacturing costs of the device for implementing the method(determination of the roll angle from the product of the yaw rate whichis fixed to the motorcycle and the velocity) are considerably lowercompared to those for a highly accurate inertial sensor system while theaccuracy is the same. The position of the sensor system on themotorcycle is not relevant since the rotational speed is the same overthe entire vehicle.

Methods for determining a roll angle on the basis of accelerationmeasurement ({umlaut over (z)}^(M) or {umlaut over (z)}^(M), ÿ^(M)) anda measurement of the rolling rate {dot over (λ)}_(M) are describedabove. The fault tolerance of these methods can be increased byfiltering the rolling rate {dot over (λ)}_(M) with a first-order highpass filter, for example with a cut-off frequency of approximately 0.01Hz.

An aspect of the invention also relates to a method for checking theplausibility of the measured value of a roll angle-determiningalgorithm. In order to check the plausibility of the method, the rollangle can be determined for the steady-state travel condition, i.e. thesecond roll angle variable, redundantly using different methods. Forexample, a roll angle variable λ₂ and, respectively, λ₂″ can bedetermined from the yaw rate {dot over (ψ)}_(M) which is fixed to themotorcycle and the velocity v as well as from the vertical acceleration{umlaut over (z)}^(M) which is fixed to the motorcycle and the lateralacceleration ÿ^(M) which is fixed to the motorcycle.

Any selection of two or more roll angle-determining methods isconceivable. The trustworthiness of the roll angle λ_(E) which isdetermined by means of the roll angle variable or variables can beestimated by comparing the results.

Furthermore, under certain circumstances a sensor fault can be detectedby the plausibility checking/the comparison. If there is a considerabledifference between the roll angle variables λ₂, λ₂′, λ₂″ which aredetermined in a variety of ways it is possible to infer a malfunction ofone of the acceleration sensors or rotational speed sensors.

If the acceleration sensors which are present measure constant valuesover a specific time period, the rolling rate {dot over (λ)}_(M) must bezero in this time period. An offset of the rolling rate sensor cantherefore be determined and compensated.

Between any two travel conditions with a roll angle of zero degrees, theintegral of the rolling rate {dot over (λ)}_(M) is zero degrees. Given aknown offset of the rolling rate sensor, the linearity fault of therolling rate sensor can be determined by means of this condition.

Systems which are critical in terms of safety require information aboutthe reliability of the roll angle signal. This reliability can bedetermined on the basis of the described method for the purpose ofplausibility checking.

A traveling motorcycle must always be in a position of equilibrium. Thisis necessary both for straight-ahead travel and for cornering. Theposition of equilibrium of the motorcycle is dependent on a large numberof different factors, for example the vehicle velocity v, thecoefficient of friction between the tire and roadway, the wheel speedsω_(I) (i=1 or 2 for the front wheel or rear wheel), the engine speed,the steering angle, the vehicle load, the inclination of the roadway,etc. These factors influence the equilibrium values for the rolling rate{dot over (λ)}_(M), the yaw rate {dot over (ψ)}_(M) and the threecomponents of the vehicle acceleration {umlaut over (x)}^(M), ÿ^(M) and{umlaut over (z)}^(M).

FIG. 6 is a schematic illustration of a fourth exemplary embodiment of amethod according to an aspect of the invention. The algorithm accordingto the example for the calculation 26 of the roll angle λ_(E) is basedon the measurements of the values for the yaw rate {dot over (ψ)}_(M),the rolling rate {dot over (λ)}_(M), the acceleration, fixed to themotorcycle, in the {umlaut over (z)}^(M) direction and the acceleration,fixed to the motorcycle, in the y direction ÿ^(M) with correspondingsensors. In order to ensure a high level of accuracy, the algorithm mustchange adaptively as a function of the travel situation. In order tomake this possible, it is necessary also to use the information from aplurality of vehicle systems (vehicle sensors), to estimate the currenttravel situation and to adapt the algorithm for the calculation 26 ofthe roll angle λ_(E) in accordance with the travel situation. For thispurpose, in block 27 the current travel situation is estimated on thebasis of one or more of the following variables: engine speed, enginetorque, steering angle, vehicle velocity v, vehicle acceleration, wheelspeeds ω_(i), state of the roadway, wheel slip, vehicle load,inclination of the roadway. This estimation is then included in thecalculation 26 of the roll angle λ_(E).

It is also necessary to take into account the fact that the theoreticalroll angle λ_(th) and the total roll angle λ_(ges) differ since thewidth of the tire is not equal to zero.

FIG. 7 is a schematic illustration of an exemplary method for adaptivelycalculating a roll angle λ_(E). In order to ensure a high degree ofaccuracy, a combination of various methods is used to calculate the rollangle λ_(E). At the same time, measurements of the rolling rate {dotover (λ)}_(M), of the yaw rate {dot over (ψ)}_(M) and of theaccelerations in the z and y direction {umlaut over (z)}^(M), ÿ^(M) arecarried out, for example with a sensor cluster. The integral 30 of therolling rate {dot over (λ)}_(M) is formed, and the result λ₁ is filteredwith a high pass filter 31. Furthermore, in block 32 the arc tangent ofthe quotient of the acceleration in the y direction ÿ^(M) is calculatedwith respect to the acceleration in the z direction {umlaut over(z)}^(M), and the result λ₂ ¹ is filtered with a low pass filter 33.Likewise, in block 34 the arc tangent of the quotient of the product ofthe yaw rate {dot over (ψ)}_(M) times the vehicle acceleration v iscalculated to form the acceleration in the z direction {umlaut over(z)}^(M), and the result λ₂ ² is filtered with a low pass filter 35. Thethree results are multiplied by corresponding weighting parameters P1,P2 and P3 (blocks 36) and summed (block 37).

Properties of the system (for example filter properties) such as, forexample, the cut-off frequencies of the individual filters 31, 33, 35and/or the weighting parameters P1, P2, P3 are changed as a function ofthe current travel situation 27 which is detected by means of at leastone of the abovementioned variables, for example the vehicle velocity v,wheel slip, wheel speeds ω_(i), engine speeds, steering angle, vehicleload, inclination of the roadway, rolling rate {dot over (λ)}_(M), yawraw {dot over (ψ)}_(M), roll angle acceleration, yaw angle acceleration,and roll angle λ_(E) (previously calculated, for example). Thedependence of the system properties, for example the dependence of thecut-off frequencies of the filters and the dependence of the weightingparameters P1, P2, P3, on these variables are determined empirically ortheoretically, stored in a control unit in the form of characteristiccurves or characteristic diagrams or calculation rules and taken intoaccount in the calculation of the roll angle. The system can be adaptedfor any travel situation and the roll angle λ_(E) of the vehicle can bedetermined accurately by automatically changing the parameters (on thebasis of the stored characteristic curves, characteristic diagrams orcalculation algorithms).

FIG. 8 is a schematic illustration of an exemplary method for adaptivedetermining a roll angle λ_(E). In order to ensure high degree ofaccuracy, a combination of various methods is used to calculate the rollangle λ_(E).

The roll angle λ_(E) is determined based on a first roll angle variableλ₁ and based on a second roll angle variable λ₂.

Subsequently an exemplary method for determining the roll angle λ_(E)based on the first and the second roll angle variables λ₁, λ₂ will bedescribed. The method takes place in a frequency domain.

A first high-pass filter 83 filters the first roll angle variable λ₁with a first cutoff frequency, which results in a filtered first rollangle variable λ₁₁. A second high-pass filter 86 filters the first rollangle variable λ₁ with a second cutoff frequency, which results in afiltered second roll angle variable λ₁₂.

A first low-pass filter 84 filters the second roll angle variable λ₂with a first cutoff frequency, which results in a filtered third rollangle variable λ₂₁. A second low-pass filter 85 filters the second rollangle variable λ₂ with a second cutoff frequency, which results in afiltered fourth roll angle variable λ₂₂ Arcus sinus function 92 isexecuted before the low pass filters 84, 85.

A first combination 89 combines the filtered first roll angle variableλ₁₁ and the filtered third roll angle variable λ₂₁ which results in afirst combined roll angle variable λ_(a).

A second combination 90 combines the filtered second roll angle variableλ₁₂ and the filtered fourth roll angle variable λ₂₂ which results in asecond combined roll angle variable λ_(b).

A third high-pass-filter 87 filters the first combined roll anglevariable λ_(a) with a third cutoff frequency. A third low-pass filter 88filters the second combined roll angle variable λ_(b) with a thirdcutoff frequency.

The first cutoff frequency is lower than the third cutoff frequency andthe third cutoff frequency is lower than the second cutoff frequency.

A third combination 91 combines the filtered first combined roll anglevariable λ_(a)′ and the filtered second combined roll angle variableλ_(b)′, which results in the roll angle λ_(E).

Particularly the combination takes place in a frequency domain and theamplitudes are added.

Due to an offset error of the roll rate sensor, an integration obtainingthe first roll angle variable λ₁ will result in a ramp function, why anoverflow will appear at some point in the integrator 93. In order tocircumvent such an overflow the integrator 93 will be resetted, as soonas the output value of the integrator 93 reaches a certain positive,respectively negative threshold. Particularly, when resetting, thecertain positive, respectively negative threshold may be subtracted,respectively added, to the output value. A jump in the output value dueto the reset or an overflow of the integrator 93 may usually bepropagated to the first high-pass filter 83 and to the second high-passfilter 86 and be detectable at the output of the first high-pass filter83 and at the output of the second high-pass filter 86. In order tocircumvent the detectable jump in the output of the first high-passfilter 83 and in the output of the second high-pass filter 86, bothhigh-pass filter 83, 86 may be resetted at the same time as theintegrator 93. To do so both high-pass filters 83, 86 may besynchronized with the integrator 93. Particularly all previous storedinput states of the integrator 93, the first high-pass filter 83 and thesecond high-pass filter 86 are resetted to zero. Particularly allprevious stored output states of the integrator 93, the first high-passfilter 83 and the second high-pass filter 86 are resetted to zero.

Due to synchronized resetting the integrator 93 and the first and thesecond high-pass filter 83, 86 an overflow, particularly an overflow ofthe integrator 93, does not affect the output of the first and/or thesecond high-pass filter 83, 86.

In the exemplary method the low-pass filters comprise anarcsin-function. The arcsin functions are applied on the signalsfiltered by the low pass filters having very low cut-off frequencies toavoid clipping due to the high noise coming from the low dynamic method,which is shown in FIG. 10. Apart from this the combination method shownin FIG. 10 corresponds to the combination method shown in FIG. 8.

There is a cross effect between angular rates due to inclinations of themeasurement system. For example, if a pitch angle α of the motorcycledoes not equal zero, the yaw rate sensor measures a portion of the rollrate {dot over (λ)}_(roadway) which is fixed to the roadway and viceversa the roll rate sensor measures a portion of the yaw rate {dot over(ψ)}_(roadway) which is fixed to the roadway. This is particularly thecase when the motorcycle moves on a circular path. This cross effect canbe eliminated based on inertial measurement. Particularly the pitchangle α is not zero, because the sensor cluster is not mountedhorizontally on the motorcycle with regard to the roadway 1 and/orbecause of heavy weight on the motorcycle causing the rear suspension tobe pushed down.

Algorithm 81 corrects the yaw rate {dot over (ψ)}^(M) which is fixed tothe motorcycle by eliminating the erroneous roll rate portion {dot over({tilde over (λ)})}^(roadway). The erroneous roll rate portion {dot over({tilde over (λ)})}^(roadway) corresponds to this cross effect.

Algorithm 97 (a multiplication) determines the roll angle on the basisof the corrected yaw rate (algorithm 81) and the velocity (correspondingto block 23 of FIG. 5).

Algorithm 82 corrects the roll rate {dot over (λ)}^(M) which is fixed tothe motorcycle by eliminating the erroneous yaw rate portion {dot over({tilde over (ψ)})}^(roadway). The erroneous yaw rate portion {dot over({tilde over (ψ)})}^(roadway) corresponds to this cross effect.

In order to eliminate these cross effects the pitch angle α has to beestimated.

Algorithm 81 and algorithm 82 estimate the pitch angle α based onlongitudinal acceleration {umlaut over (x)}^(M) which is fixed to themotorcycle and/or based on vertical acceleration {umlaut over (z)}^(M)which is fixed to the motorcycle and/or based on the overallacceleration of the motorcycle {dot over (ν)} and/or based on thegravity g. Alternatively solely one of these algorithms estimates thepitch angle α and the other algorithm is provided with the estimatedpitch angle α.

FIG. 9 exemplary, schematically illustrates at least the relation oflongitudinal acceleration {umlaut over (x)}^(M) which is fixed to themotorcycle, overall acceleration of the motorcycle {dot over (ν)}, thevertical acceleration {umlaut over (z)}^(M) which is fixed to themotorcycle and pitch angle α.

The longitudinal acceleration sensor measures a longitudinalacceleration {umlaut over (x)}^(M) which is fixed to the motorcycle. Thelongitudinal acceleration {umlaut over (x)}^(M) results from a gravityportion {umlaut over (x)}₁ influencing the longitudinal accelerationmeasurement depending on the pitch angle α and from an overallacceleration portion of the motorcycle {umlaut over (x)}₂ influencingthe longitudinal acceleration measurement depending on the pitch angleα:

{umlaut over (x)} ^(M) ={umlaut over (x)} ₁ +{umlaut over (x)} ₂  (15)

The vertical acceleration sensor measures a vertical acceleration{umlaut over (z)}^(M) which is fixed to the motorcycle. The verticalacceleration {umlaut over (z)}^(M) results from a gravity portion{umlaut over (z)}₁ influencing the vertical acceleration measurementdepending on the pitch angle α and from an overall acceleration portionof the motorcycle {umlaut over (z)}₂ influencing the verticalacceleration measurement depending on the pitch angle α:

{umlaut over (z)} ^(M) ={umlaut over (z)} ₁ +{umlaut over (z)} ₂  (15)

According to the following approach the calculation of pitch angle α canbe deduced:

$\begin{matrix}{\frac{{\overset{¨}{x}}^{M}}{{\overset{¨}{z}}^{M}} = \frac{{g*\sin \; \alpha} - {\overset{.}{v}*\cos \; \alpha}}{{g*\cos \; \alpha} + {\overset{.}{v}*\sin \; \alpha}}} & \left( {15a} \right) \\{{{{{\overset{¨}{x}}^{M}\left( {{g*\cos \; \alpha} + {\overset{.}{v}*\sin \; \alpha}} \right)} = {z^{M}\left( {{g*\sin \; \alpha} - {\overset{.}{v}*\cos \; \alpha}} \right)}}}\frac{1}{\cos \; \alpha}} & \left( {15b} \right) \\{{{{\overset{¨}{x}}^{M}g} + {{\overset{¨}{x}}^{M}\overset{.}{v}\; \tan \; \alpha}} = {{{\overset{¨}{z}}^{M}g\; \tan \; \alpha} - {{\overset{¨}{z}}^{M}\overset{.}{v}}}} & \left( {15c} \right) \\{{{{\overset{¨}{x}}^{M}g} + {{\overset{¨}{z}}^{M}\overset{.}{v}}} = {\tan \; {\alpha \left( {{{\overset{¨}{z}}^{M}g} - {{\overset{¨}{x}}^{M}\overset{.}{v}}} \right)}}} & (16) \\{\alpha = {{\tan^{- 1}\left( \frac{{{\overset{¨}{x}}^{M}g} + {{\overset{¨}{z}}^{M}\overset{.}{v}}}{{{\overset{¨}{z}}^{m}g} - {{\overset{¨}{x}}^{M}\overset{.}{v}}} \right)} \approx \left( \frac{{{\overset{¨}{x}}^{M}g} + {{\overset{¨}{z}}^{M}\overset{.}{v}}}{{{\overset{¨}{z}}^{M}g} - {{\overset{¨}{x}}^{M}\overset{.}{v}}} \right)}} & (17)\end{matrix}$

Consequently the pitch angle α is obtainable based on longitudinalacceleration {umlaut over (x)}^(M) which is fixed to the motorcycle andbased on vertical acceleration {umlaut over (z)}^(M) which is fixed tothe motorcycle and based on the overall acceleration of the motorcycle{dot over (ν)} and based on the gravity g, particularly according toformula 17. More particularly preferred the arctan function can beneglected.

Algorithm 81 determines corrected yaw rate {dot over (ψ)}^(roadway)which is fixed to the roadway. The erroneous roll rate portion {dot over({tilde over (λ)})}^(roadway) is determined by multiplying the roll rate{dot over (λ)}^(M) which is fixed to the motorcycle with the pitch angleα. Particularly the erroneous roll rate portion {dot over ({tilde over(λ)})}^(roadway) is determined by multiplying the roll rate {dot over(λ)}^(M) with the sinus of the pitch angle α. The corrected yaw rate{dot over (ψ)}^(roadway) may particularly be determined by subtractingthe erroneous roll rate portion {dot over ({tilde over (ψ)})}^(roadway)from the yaw rate {dot over (ψ)}^(M):

{dot over ({tilde over (λ)})}^(roadway)={dot over (λ)}^(M)*sin(α)  (18)

{dot over (ψ)}={dot over (ψ)}^(M)_{dot over ({tilde over(λ)})}^(roadway)  (19)

Algorithm 82 determines corrected roll rate {dot over (λ)}^(roadway)which is fixed to the roadway. The erroneous yaw rate portion {dot over({tilde over (ψ)})}^(roadway) is determined by multiplying the yaw rate{dot over (ψ)}^(M) which is fixed to the motorcycle with the pitch angleα. Particularly the erroneous yaw rate portion {dot over ({tilde over(ψ)})}^(roadway) is determined by multiplying the yaw rate {dot over(ψ)}^(M) with the sinus of the pitch angle α. Particularly preferredduring high dynamic rolling and/or always a corrected erroneous yaw rateportion {dot over ({tilde over ({tilde over (ψ)})})}^(roadway) isdetermined by dividing the erroneous yaw rate portion {dot over ({tildeover (ψ)})}^(roadway) by the squared roll rate ({dot over (λ)}^(M))².The corrected roll rate {dot over (λ)}^(roadway) can particularly bedetermined by subtracting the erroneous yaw rate portion {dot over({tilde over (ψ)})}^(roadway) or the corrected erroneous yaw rateportion {dot over ({tilde over ({tilde over (ψ)})})}^(roadway) from theroll rate {dot over (λ)}^(M):

$\begin{matrix}{{\overset{\overset{\sim}{.}}{\psi}}^{roadway} = {{\overset{.}{\psi}}^{M} \cdot {\sin (\alpha)}}} & (20) \\{{\overset{\overset{\overset{\sim}{\sim}}{.}}{\psi}}^{roadway} = \frac{{\overset{\overset{\sim}{.}}{\psi}}^{roadway}}{\left( {\overset{.}{\lambda}}^{M} \right)^{2}}} & (21) \\{{\overset{.}{\lambda}}^{roadway} = {{\overset{.}{\lambda}}^{M} - {\overset{\overset{\sim}{.}}{\psi}}^{roadway}}} & (22) \\{{\overset{.}{\lambda}}^{roadway} = {{\overset{.}{\lambda}}^{M} - {\overset{\overset{\overset{\sim}{\sim}}{.}}{\psi}}^{roadway}}} & (23)\end{matrix}$

In the following a compensation method is described for the secondmethod determining the second roll angle variable λ₂ in order toincrease the precision of the calculation based on vertical centrifugalacceleration. Thereby algorithm 94 estimates a centrifugal forcef_(rad). The centrifugal force is proportional to the squared roll rate{dot over (λ)}^(M) multiplied with a radius r_(COG). The center ofgravity of the motorcycle moves on the circumference of a circle, ofwhich the radius r_(COG) is the distance between the tire contact pointon the ground and the center of gravity.

f _(rad)˜{dot over (λ)}^(M) ² *r _(COG)  (24)

If the center of gravity of the motorcycle is on the vertical axis ofthe motorcycle this mentioned force is only measured by the verticalacceleration sensor.

Due to body leaning the center of gravity can shift with regard to thevertical axis of the motorcycle. In this case the centrifugal forcef_(rad) is partly measured by the lateral acceleration sensor, which hasto be compensated.

{umlaut over ({tilde over (y)})}=ÿ ^(M)−({umlaut over (z)} ^(M) −f_(rad))  (25)

Based on the estimated centrifugal force f_(rad), on the lateralacceleration ÿ^(M) and on the vertical acceleration {umlaut over(z)}^(M) a centrifugal compensation takes place in algorithm 98according to e.g. formula 25.

In the following a compensation method is described for the secondmethod determining the second roll angle variable λ₂ in order toincrease the precision of the calculation based on the common effect ofthe lateral acceleration and the roll rate. Algorithm 95 estimates arapid leaning force f_(rap) _(_) _(leaning). The rapid leaning forcef_(rap) _(_) _(leaning) is proportional to the derivative of the rollrate {umlaut over (λ)}^(M) and the distance between the tire contactpoint on the ground and the mounting location of the lateralacceleration sensor r_(sensor).

Based on the estimated rapid leaning force f_(rap) _(_) _(leaning) andon the lateral acceleration ÿ^(M) a rapid leaning compensation takesplace in algorithm 98 according to e.g. formula 27. Thereby the commoneffect of the lateral acceleration and the roll rate is compensated.

f _(rap) _(_) _(leaning)˜{umlaut over (λ)}^(M) *T _(sensor)  (26)

{umlaut over ({tilde over (y)})}^(M) =ÿ ^(M)−(f _(rap) _(_)_(leaning))  (27)

In the following a compensation method is described for the secondmethod determining the second roll angle variable λ₂ in order toincrease the precision of the calculation by compensating the differencebetween the total roll angle λ_(ges) and the physically active rollangle λ_(th). Algorithm 96 estimates a tire profile compensation value.Thereby the gravity g is eliminated in the vertical acceleration {umlautover (z)}^(M). This result is multiplied by the yaw rate ψ^(M).

Based on the estimated tire profile compensation value and on thelateral acceleration ÿ^(M) a tire profile compensation takes place inalgorithm 98 according to e.g. formula 28.

{umlaut over ({tilde over (y)})}^(M) =ÿ ^(M)−({umlaut over (z)} ^(M)−g)*ψ^(M)  (28)

Algorithm 98 determines the second roll angle variable λ₂ using thesecond method. Particularly at least one of the previously describedcompensation methods are applied, wherein the corrected lateralacceleration {umlaut over ({tilde over (y)})}^(M) can be used fordetermining the second roll angle variable λ₂.

Particularly the corrected yaw rate {dot over (ψ)}^(roadway) which isfixed to the roadway and the corrected roll rate {dot over(λ)}^(roadway) which is fixed to the roadway are applied for determiningthe first λ₁ and/or the second λ₂ roll angle variable.

Alternatively an aspect of the invention can be described as follows.

Particularly the method to determine the roll angle of a motorcycle isusing inertial measurement signals:

-   -   a. Yaw rate    -   b. Roll rate    -   c. Longitudinal-, lateral- and vertical-acceleration    -   d. Vehicle velocity

Preferably cross effects between angular rates due to the inclinationsof the measurement system are eliminated based on the inertialmeasurement.

Preferably the motorcycle roll angle is calculated as a combination ofroll angles calculated by methods providing roll angle values withdifferent properties.

Preferably the combination is calculated by multiple levels of filteringand summing in order to improve noise cancellation and to reduce offseteffects.

Preferably one of the roll angle calculation methods is using a specialresettable integrator together with a specially prepared high-passfilter to eliminate roll-rate offset effects.

Preferably one of the roll angle calculation methods is using acompensation method to increase the precision of the calculation basedon the vertical centrifugal acceleration.

Preferably one of the roll angle calculation methods is using acompensation method to increase the precision of the calculation basedon the common effect of the lateral acceleration and the roll rate.

1. A method to determine a roll angle (λ_(E)) of a vehicle, comprising:calculating the roll angle (λ_(E)) as a combination of at least a firstroll angle variable (λ₁) and a second roll angle variable (λ₂),determining wherein the first roll angle variable (λ₁) from an acquiredrolling rate ({dot over (λ)}_(m)) of the vehicle using a first method,and determining the second roll angle variable (λ₂) from one or morefurther vehicle movement dynamics characteristic variables using asecond method.
 2. The method according to claim 1, wherein thecombination comprises multiple levels, wherein each level comprises atleast one filtering step and at least one combination step.
 3. Themethod according to claim 2, wherein the number of levels is x, whereinthe y-st level comprises 2^(x−y+1) filtering steps and 2^(x−y)combination steps, wherein the output of level y is the input of levely+1, and wherein in the y-st level 2^(x−y) cutoff frequencies areapplied.
 4. The method according to claim 1, wherein the first rollangle variable (λ₁) has different characteristics than the second rollangle variable (λ₂).
 5. The method according to claim 1, wherein thesecond roll angle variable (λ₂) is determined from: a yaw rate of thevehicle and a vehicle velocity; and/or a lateral acceleration andvertical acceleration of the vehicle.
 6. The method according to claim1, further comprising eliminating cross effects between angular ratesdue to the inclinations of the measurement system based on the inertialmeasurement.
 7. The method according to claim 1, wherein one of the rollangle variable determination methods applies a resettable integrator incombination with a resettable high-pass filter to eliminate roll-rateoffset effects.
 8. The method according to claim 7, wherein the firstmethod applies an integrator for determining the first roll anglevariable (λ₁), wherein the integrator and direct subsequent high-passfilters, are reset essentially simultaneous as soon as the output of theintegrator reaches a predefined threshold.
 9. The method according toclaim 1, wherein one of the roll angle variable determination methods isusing a compensation method to increase the precision of the calculationbased on the vertical centrifugal acceleration.
 10. The method accordingto claim 1, wherein one of the roll angle variable determination methodsis using a compensation method to increase the precision of thecalculation based on the common effect of the lateral acceleration andthe roll rate.
 11. The method according to claim 1, wherein at least thefirst method provides roll angle values with particularly high accuracyfor rapidly changing roll angle values, and at least the second methodprovides roll angle values with particularly high accuracy for steadyroll angle values, wherein the combination takes place in a frequencydomain.
 12. The method according to claim 1, wherein an amplitude ofhigh frequencies of the roll angle variable of the first method isweighted higher than an amplitude of high frequencies of the roll anglevariable of the second method, wherein an amplitude of low frequenciesof the roll angle variable of the second method is weighted higher thanan amplitude of low frequencies of the roll angle variable of the firstmethod, wherein an amplitude of mid frequencies are weighted similarly.13. The method according to claim 1, wherein a first combination,combining the roll angle variable of the first method high-passedfiltered with a first cutoff frequency and the roll angle variable ofthe second method low-passed filtered essentially with the first cutofffrequency, a second combination, combining the roll angle variable ofthe first method high-passed filtered with a second cutoff frequency andthe roll angle variable of the second method low-passed filteredessentially with the second cutoff frequency, and a third combination,combining the roll angle variable result of the first combinationlow-passed filtered with a third cutoff frequency and the roll anglevariable result of the second combination high-passed filteredessentially with the third cutoff frequency, and wherein the first, thesecond and the third cutoff-frequencies are different.
 14. The methodaccording to claim 13 wherein the third cutoff frequency lies betweenthe first cutoff frequency and the second cutoff frequency
 15. A deviceto determine a roll angle (λ_(E)) of a vehicle, comprising: acombination circuit used to combine at least a first roll angle variable(λ₁) and a second roll angle variable (λ₂) to calculate a roll angle(λ_(E)), wherein, the first roll angle variable (λ₁) is determined froman acquired rolling rate ({dot over (λ)}_(m)) of the vehicle, and thesecond roll angle variable (λ₂) is determined using at least one vehiclemovement dynamics characteristic variable.